Sensitive determination of prostate-specific antigen with graphene quantum dot-based fluorescence aptasensor using...

A novel fluorescence aptasensor of prostate-specific antigen (PSA) was established using few-layer vanadium carbide (FL-V₂CT_x) nanosheet as a quencher. First, FL-V₂CT_x was prepared by the delamination of multi-layer V₂CT_x (ML-V₂CT_x) with tetramethylammonium hydroxide. The aptamer-carboxyl graphene quantum dots (CGQDs) probe was prepared by combining the aminated PSA aptamer and CGQDs. Then, the aptamer-CGQDs were absorbed onto the surface of FL-V₂CT_x by hydrogen bond interaction, which led to the decrease in fluorescence of aptamer-CGQDs due to photoinduced energy transfer. After addition of PSA, PSA-aptamer-CGQDs complex was released from FL-V₂CT_x. The fluorescence intensity of aptamer-CGQDs-FL-V₂CT_x with PSA was higher than that without PSA. The FL-V₂CT_x-based fluorescence aptasensor provided a PSA detection linear range from 0.1 to 20 ng mL^-1 with detection limit of 0.03 ng mL^-1. The ΔF value of fluorescence intensities for aptamer-CGQDs-FL-V₂CT_x with and without PSA was 5.6, 3.7, 7.7, and 5.4 times of ML-V₂CT_x, few-layer titanium carbide (FL-Ti₃C₂T_x), ML-Ti₃C₂T_x and graphene oxide aptasensors, respectively, indicating the advantage of FL-V₂CT_x. The aptasensor had high selectivity for PSA detection compared with some proteins and tumor markers. This proposed method had convenience and high sensitivity for PSA determination. The determination results of PSA in human serum samples using the aptasensor were consistent with those by chemiluminescent immunoanalysis. The fluorescence aptasensor can be successfully applied for PSA determination in serum samples of prostate cancer patients.